media: v4l: ioctl: Fix memory leak in video_usercopy

commit fb18802a338b36f675a388fc03d2aa504a0d0899 upstream.

When an IOCTL with argument size larger than 128 that also used array
arguments were handled, two memory allocations were made but alas, only
the latter one of them was released. This happened because there was only
a single local variable to hold such a temporary allocation.

Fix this by adding separate variables to hold the pointers to the
temporary allocations.

Reported-by: Arnd Bergmann <arnd@kernel.org>
Reported-by: syzbot+1115e79c8df6472c612b@syzkaller.appspotmail.com
Fixes: d14e6d76ebf7 ("[media] v4l: Add multi-planar ioctl handling code")
Cc: stable@vger.kernel.org
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index 699e5f8e0a7100e775d0655deb42dc35b6460a89..2cdd6d84e51962eb85d40729932e49e5373da2aa 100644 (file)
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -2804,7 +2804,7 @@ video_usercopy(struct file *file, unsigned int cmd, unsigned long arg,
               v4l2_kioctl func)
 {
        char    sbuf[128];
-       void    *mbuf = NULL;
+       void    *mbuf = NULL, *array_buf = NULL;
        void    *parg = (void *)arg;
        long    err  = -EINVAL;
        bool    has_array_args;
@@ -2859,20 +2859,14 @@ video_usercopy(struct file *file, unsigned int cmd, unsigned long arg,
        has_array_args = err;
 
        if (has_array_args) {
-               /*
-                * When adding new types of array args, make sure that the
-                * parent argument to ioctl (which contains the pointer to the
-                * array) fits into sbuf (so that mbuf will still remain
-                * unused up to here).
-                */
-               mbuf = kmalloc(array_size, GFP_KERNEL);
+               array_buf = kmalloc(array_size, GFP_KERNEL);
                err = -ENOMEM;
-               if (NULL == mbuf)
+               if (array_buf == NULL)
                        goto out_array_args;
                err = -EFAULT;
-               if (copy_from_user(mbuf, user_ptr, array_size))
+               if (copy_from_user(array_buf, user_ptr, array_size))
                        goto out_array_args;
-               *kernel_ptr = mbuf;
+               *kernel_ptr = array_buf;
        }
 
        /* Handles IOCTL */
@@ -2891,7 +2885,7 @@ video_usercopy(struct file *file, unsigned int cmd, unsigned long arg,
 
        if (has_array_args) {
                *kernel_ptr = (void __force *)user_ptr;
-               if (copy_to_user(user_ptr, mbuf, array_size))
+               if (copy_to_user(user_ptr, array_buf, array_size))
                        err = -EFAULT;
                goto out_array_args;
        }
@@ -2911,6 +2905,7 @@ video_usercopy(struct file *file, unsigned int cmd, unsigned long arg,
        }
 
 out:
+       kfree(array_buf);
        kfree(mbuf);
        return err;
 }